Hard, abrasion resistant coatings are used over a variety of substrates, including cement, wood, and porous substrates. Particularly demanding substrates include horizontal substrates such as sidewalks, floor tiles, cement garage floors and decks. Unfortunately, many of the commercially available coatings in use today for these substrates suffer from problems such as poor adhesion, or poor water resistance (e.g., “blushing”).
Cement and fiber cement substrates have an additional issue, in that they typically require hard, abrasion resistant coatings with excellent adhesion. In the past, this has been addressed by using higher-Tg polymer systems. Unfortunately, volatile organic content (VOC) solvents generally must be used to achieve proper coalescence of higher-Tg polymers. Consequently, there is an unmet need to develop acceptable low VOC aqueous based coatings that are hard, blush resistant, abrasion resistant and offer excellent adhesion to cement and fiber cement substrates.
In addition, there is an unmet need for improved fiber cement articles that resist damage from repeated freezing and thawing of water absorbed into the substrate. This need is particularly acute in colder climates where freeze-thaw mechanisms can occur. Prefinished fiber cement siding products can also be visually marred or damaged during storage. One damage mechanism is caused by the heavy boards being stacked against or atop one another. In some cases the weight against the bottom boards may exceed 6 kg/cm2 or even 10 kg/cm2, and may damage the finish. In particular, the peaks of the embossed surface can be crushed, and the flattened peaks can appear as glossy spots.